1. Field of Invention
The present disclosure relates to estimating properties of cement that lines a wellbore by direct interaction with the cement. More specifically, the present disclosure is directed to a method of estimating cement properties by penetrating the cement, and monitoring an amount of power or energy required for the penetration. The method further includes obtaining core samples from portions of each string, each layer of cement, and formation adjacent the wellbore.
2. Description of Prior Art
Hydrocarbon producing wellbores are typically lined with casing that is bonded to the wellbore with cement. The cement is injected within the annulus formed between the outer diameter of the casing and the inner diameter of the wellbore. The cement adheres the casing within the wellbore, and also isolates adjacent zones within the formation from one another. Isolating adjacent zones can be important when one of the zones contains oil or gas and the other zone includes a non-hydrocarbon fluid such as water. The properties of the cement behind the casing are of significant importance to the integrity of the well. Should the cement surrounding the casing be defective and fail to provide isolation of the adjacent zones, water or other undesirable fluid can migrate into the hydrocarbon producing zone thus diluting or contaminating the hydrocarbons within the producing zone. Faulty cement sometimes allows hydrocarbons to navigate up the wellbore between the casing and wellbore wall and to a location having an ignition source.
Known techniques for identifying damaged cement include installing downhole sensors for detecting fluid leakage, or deploying downhole tools that interrogate the wellbore. Example downhole tools for analyzing the integrity of wellbore cement include transducers that emit acoustic waves into the casing. Attenuation of the acoustic waves can be analyzed to estimate efficacy and integrity of the cement bond. The types of transducers used for inducing and recording the acoustic waves include piezoelectric devices and electrical magnetic acoustic transducers.